Food miles in perspective

At first glance reducing food miles seems an excellent way to reduce carbon emissions, because it limits emissions caused by planes, trucks, boats and trains moving food. But if you’re not careful cutting food miles can easily increase your food’s carbon footprint.

The most important thing to remember about food miles is that they are only part of the bigger food emissions story. A person’s foodprint is actually dominated by production emissions, and food transport makes up just a tenth of food emissions up to the point of sale.

The virtues of eating seasonally

The problem of focusing purely on food miles to reduce emissions is easy enough to understand. The classic example is the much-loved tomato.

In cooler climates like northern Europe, Canada and the north states of the US people eat tomatoes all year round, despite the local weather not being conducive to growing them. Winter tomatoes in these places are either hot housed locally, using significant amounts of energy, or imported from warmer climates like Spain or Mexico.

When you analyse the respective carbon footprints of local and imported tomatoes it becomes clear that production emissions can easily dwarf transport emissions. A good example comes from a 1998 paper by Annika Carlsson which showed that tomatoes imported from Spain to Sweden have much lower footprints that those locally grown.

Despite travelling a greater distance Spanish tomatoes imported to Sweden have a far smaller footprint than locally grown ones. This is because the emissions generated to heat and light greenhouses in northern Europe far exceed the transport emissions of bringing tomatoes in from Spain.

Similar results have been found when comparing out of season English tomatoes to Spanish imports, although there are also some noble exceptions to this rule. For example both in Sweden and England it is possible to get winter tomatoes raised using waste heat, renewable energy and highly efficient hydroponic systems.

So does this mean targeting food miles is a complete waste of time? Notcompletely. But if your motivation for eating more local food is carbon emissions, then it is better to try to eat seasonal local food.

By eating food that is both in season and local you can be more certain that both production emissions and transport emissions are limited. You can often avoid them being refrigerated in stores too. Even more importantly, seasonal food just tastes so much better.

Where I live in the UK eating a tomato or strawberry from Spain doesn’t taste anything like as sweet as one in season from a local farm. Not only are many imported varieties a bit bland to begin with, but they suffer from time in storage, being refrigerated and forced ripening.

Of course not even locally grown tomatoes can compare to eating one of your own. 😉

Grounding flying food?

If you are going to try and tackle food miles, the natural place to start is with flying food, but even then its not always simple.

From an emissions perspective food miles are not created equal. In the UK just 1% of food transport is done by plane, but it accounts for 11% of emissions.

Using figures from DEFRA we can compare the emissions that result moving a tonne of food by different means.

The figures are pretty stark.

Food that flies can generate more than one hundred times the carbon emissions per kilometre of food that travels by ship.

If I eat a banana that has been shipped to the UK from Colombia its transport emissions are relatively small. But if I eat an avocado flown in from Mexico they are huge.

Depending on where you live the food that flies will be very different. European countries get a lot of beans, sweetcorn, asparagus, podded peas, limes, avocados, spring onions, pineapple, grapes and sweet potato from Africa and Central America. There is also a lot of fish flown in from Asia and South America. Food that is flown tends to have relatively high value for its weight, is perishable and can’t be produced as cheaply locally.

Limiting the amount of flying food can be a way to help reduce food transport emissions, but you need to think about those decisions in the proper context. Both in terms of total emissions and economic impact. If you know the food you are eating is shipped in from a far, the chances are those food miles create relatively few carbon emissions while providing valuable income to farmers in Africa, South America and Asia.

However even when food has been flown in, it can still sometimes be less carbon intensive than things grown locally. This is because the carbon intensity of production in Africa for example may be many fold lower than that in Europe, more than offsetting the emissions from the food miles.

Viewing food miles in isolation can be terribly misleading. You need to focus on the whole supply chain.

It’s a curious area isn’t it. Need to look a whole picture. I get so frustrated when people buy local but hot housed flowers for environmental reasons in Europe, when in reality the Kenyan ones have a fraction of the footprint and support needy smallholders

Debbie Dean

Hey Lindsay, I edit a journal for economics and business teachers in the UK. I am running an article in the next edition on the economics behind fairtrade in preparation for fairtrade fortnight. I wanted to look at another piece to balance the picture and I was wondering you would mind if your piece is being used as another viewpoint?

Lindsay Wilson

How curious. Pertaining to food miles in particular? This piece only really looks at emissions, and the data is solid. If you start considering welfare implications for countries selling the produce it becomes a bit more confusing.

A study of New Zealand lamb found that lamb grown in New Zealand and shipped to the Smithfield meat market in the UK has a quarter of the carbon footprint of lamb grown in the UK and trucked to the Smithfield market. This startling difference was because of the low intensity farming methods in New Zealand. The results for dairying were similar but less startling because New Zealand dairying is outdoor and free range, but has higher fertilizer inputs than lamb production on hill country.

Lindsay Wilson

I’m pretty sure the NZ figure was only compared to two Welsh versions that were huge (50 kg CO2e/kg) because of their effect on peat bogs. With more realistic comparison its only 10-20% better than UK lamb. Again shipping was only 5% or so